Can someone please define what each of the values mean? From reading the various threads, it looks like range is -1 through 10, only integer values. Is this correct? I know -1 means auto-select. But what to all the rest of the values mean? Can someone please post the definitions?

Different cores simply means different algorithms used by d.net client to maximize computation with your current hardware.

By maximizing computations means crunching more keys/sec.
If you look at your task, you'll see, how fast your tasks were completed.
The higher speed, the better you're, cause it will take less time to complete a work unit.

Thanks for the answer, but I am not sure what to do with the answer: -1 should be best, but maybe not.

Yes, I can look at the performance of a particular task, but that does not tell me how "good" that performance is, or how it would have compared to the exact same task with a different value. How do I know this?
____________
Dublin, CA
Team SETI.USA

Can someone please define what each of the values mean? From reading the various threads, it looks like range is -1 through 10, only integer values. Is this correct? I know -1 means auto-select. But what to all the rest of the values mean? Can someone please post the definitions?

you can look yourself by starting the app from a command prompt with "--config".

So I did the bench test and found core 3 was significantly faster. As such I configured the app to use core 3. From the results since I made that configuration change the core setting seems to be ignored at the app continues to use core 0

So I did the bench test and found core 3 was significantly faster. As such I configured the app to use core 3. From the results since I made that configuration change the core setting seems to be ignored at the app continues to use core 0

You have to configure it in your project preferences page, here at the project. If you configure it from the command line, it gets over-written by the project preferences with the next task.
____________
Dublin, CA
Team SETI.USA

So I did the bench test and found core 3 was significantly faster. As such I configured the app to use core 3. From the results since I made that configuration change the core setting seems to be ignored at the app continues to use core 0

I can only speak for myself but selecting any other core than the default -1 didn't work with the windows 1.01 wrapper/app (The app exits and does nothing, after ten retries it's calculation error time). The Linux 1.01 wrapper/app happily ignores the setting (Core #7 is the fastest here).

Note: The Linux BOINC client just downloaded the new 1.02 wrapper/app. I have aborted all 1.01 tasks. 1.02 does work as expected.

[May 18 14:06:41 UTC] Core #7 is significantly faster than the default core.
The GPU core selection has been made as a tradeoff between core speed
and responsiveness of the graphical desktop.
Please file a bug report along with the output of -cpuinfo
only if the the faster core selection does not degrade graphics performance.

If the selected core makes problems (laggy screen updates, too much CPU load, GPUs glowing red) you can try a another core. Cores number 9, 10 and 11 use the same code as core number 1 but coordinate the CPU and the GPU by different methods. The other cores are also variations of core #1 but they differ in the way they divide the work that is sent to the multiprocessing units of the GPU.

So I did the bench test and found core 3 was significantly faster. As such I configured the app to use core 3. From the results since I made that configuration change the core setting seems to be ignored at the app continues to use core 0

You have to configure it in your project preferences page, here at the project. If you configure it from the command line, it gets over-written by the project preferences with the next task.

So that doesn't make any sense. What if you have more than one system running different cards and core 1 is best on one card core 2 on the other etc etc... shouldn't that be set per card, not at the project level?

What if you have more than one system running different cards and core 1 is best on one card core 2 on the other etc etc... shouldn't that be set per card, not at the project level?

That is what you use the different locations for. For example, you can have for example, Home (with "3") for 5870s, and Work (with "1") for my 4870s. Then assign the machines to the locations accordingly.
____________
Dublin, CA
Team SETI.USA

Based on the information in this thread I tried core 3 on both an HD5850 and HD5770. Core 0 (auto detected by selecting -1) was faster here on both. Auto (0) was much faster on the HD5770 and a bit faster than 3 on the HD5850. This was determined by running several complete WUs and comparing both the keys/sec and the completion time for the same credit values. YMMV.